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The conversion of CO2to generate high-value-added chemicals has become one of the hot research topics in green synthesis. Thereinto, the cyclization reaction of propargylic amines with CO2is highly attractive because the resultant oxazolidinones are widely found in pharmaceutical chemistry. Cu(I)-based metal–organic frameworks (MOFs) as catalysts exhibit promising application prospects for CO2conversion. However, their practical application was greatly limited due to Cu(I) being liable to disproportionation or oxidization. Herein, the solid copper(I) iodide thorium-based porous framework {[Cu5I6Th6(μ3-O)4(μ3–OH)4(H2O)10(L)10]·OH·4DMF·H2O}n(1) (HL = 2-methylpyridine-4-carboxylic acid) constructed by [Th6] clusters and [CuxIy] subunits was successfully prepared and structurally characterized. To our knowledge, this is the first copper(I) iodide-based actinide organic framework. Catalytic investigations indicate that 1can effectively catalyze the cyclization of propargylic amines with CO2under ambient conditions, which can be reused at least five times without a remarkable decline of catalytic activity. Importantly, 1exhibits excellent chemical stability and the oxidation state of Cu(I) in it can remain stable under various conditions. This work can provide a valuable strategy for the synthesis of stable Cu(I)-MOF materials.

Developing efficient heterogeneous catalysts for chemical fixation of CO2to produce high-value-added chemicals under mild conditions is highly desired but still challenging. Herein, we first reported an approach to prepare a novel catalyst (Ag@NCNFs), featuring Ag nanoparticles (NPs) embedded within porous nitrogen-doped carbon nanofibers (NCNFs), via growing a Ag metal–organic framework on one-dimensional electrospun nanofibers followed by pyrolysis. Benefiting from the abundant nitrogen species and porous structure, Ag NPs is well dispersed in the obtained Ag@NCNFs. Catalytic studies indicated that Ag@NCNFs exhibited excellent catalytic activity for the three-component coupling reaction of CO2, secondary amines, and propargylic alcohols to generate β-oxopropylcarbamates under mild conditions with a turnover number (TON) of 16.2, and it can be recycled and reused at least 5 times without an obvious decline in catalytic activity. The reaction mechanism was clearly clarified by FTIR, NMR, 13C isotope labeling, control experiments, and density functional theory calculations. The results suggest that Ag@NCNFs and 1,8-diazabicyclo[5.4.0]undec-7-ene can synergistically activate propargylic alcohol to react with CO2, and then the generated α-alkylidene cyclic carbonate was invaded by secondary amine to produce β-oxopropylcarbamate. Importantly, to the best of our knowledge, this is the first experimental and theoretical investigation on this reaction.

Four new and interesting Ln4clusters formulated as [Ln4(NO3)2(acac)4(HL1)2(CH3OH)2]·2(CH3CN)] (Ln = Gd(1), Dy(2); H4L1 = 2-(hydroxymethyl)-2-(((2-hydroxynaphthalen-1-yl)methylene)amino)propane-1,3-diol); acac = acetylacetone) and [Ln4(NO3)2(acac)4(L2)2(CH3CH2OH)2] (Ln = Gd(3), Dy(4); H3L2 = 2-(((2-hydroxynaphthalen-1-yl)methylene)amino)-2-methylpropane-1,3-diol; acac = acetylacetone) were designed and constructed. Single-crystal X-ray studies indicate that all clusters have a defect dicubane topology in which four Ln(III) are on a plane bond with an arrangement of a parallelogram with the μ3-O bridge. The difference between the two series of clusters lies in the change of the ligand substituent and terminal coordinated solvent molecules. All Ln(III)-based clusters 1–4have exhibited excellent solvent stability. The magnetic investigation suggests that clusters 1and 3possess a different magnetothermal effect (−ΔSm= 35.24 J kg–1K–1for 1, and −ΔSm= 36.68 J kg–1K–1for 3). In addition, the diversity in the environment of the metal center leads to the distinct dynamic behavior of Ueff/kB(21.27 K for 2and 1.96 K for 4) and τ0(1.43 × 10–7s for 2and 2.43 × 10–6s for 4). More importantly, clusters 1–4as heterogeneous catalysts can efficiently catalyze the reaction of CO2with bromopropylene oxide and aromatic amine to synthesize oxazolidinones under mild conditions. By comparison, clusters 1and 2show higher catalytic activity than 3and 4, in which the Brønsted acidic −OH groups working together with Lewis acid metal sites improve the catalytic activity of Ln(III)-based clusters 1and 2. To the best of our knowledge, it is the first example of Ln(III)-based clusters that show good magnetic property and high catalytic activity simultaneously by regulating the coordination environment of Ln(III) ions. Our work provided a promising direction for regulating properties of multifunctional polynuclear Ln(III)-based clusters via changing the coordinated environment of the metal center. It also helps inspire the development of polynuclear Ln(III)-based multifunctional materials.

The conversion of CO2as a C1 source into value-added products is an attractive alternative in view of the green synthesis. Among the reported approaches, the cyclization reaction of aziridines with CO2is of great significance since the generated N-containing cyclic skeletons are extensively found in pharmaceutical chemistry and industrial production. However, a low turnover number (TON) and homogeneous catalysts are often involved in this catalytic system. Herein, one novel copper–organic framework {[Cu2(L4–)(H2O)2]·3DMF·2H2O}n(1) (H4L = 2′-fluoro-[1,1′:4′,1″-Terphenyl]-3,3″,5,5″-tetracarboxylic acid) assembled by nanosized [Cu12] cages was successfully synthesized and structurally characterized, which exhibits high CO2/N2selectivity due to the strong interactions between CO2and open Cu(II) sites and ligands in the framework. Catalytic investigations suggest that 1as a heterogeneous catalyst can effectively catalyze the cyclization of aziridines with CO2, and the TON can reach a record value of 90.5. Importantly, 1displays excellent chemical stability, which can be recycled at least five times. The combination explorations of nuclear magnetic resonance (NMR), 13C-isotope labeling experiments, and density functional theory (DFT) clearly uncover the mechanism of this aziridine/CO2coupling reaction system, in which 1and tetrabutylammonium bromide (TBAB) can highly activate the substrate molecule, and the synergistic catalytic effect between them can greatly reduce the reaction energy barrier from 51.7 to 36.2 kcal/mol.

A series of new Ln8clusters [Ln8(acac)4(HL)4(L)2(μ3-O)4(C2H5O)4]·2C2H5OH·2CH2Cl2(Ln(III) = Gd (1), Dy (2), and Ho (3); Hacac = acetylacetone and H2L = 2-hydroxy-benzoic acid (5-hydroxymethyl-furan-2-ylmethylene)-hydrazide) have been designed and constructed using a multiple coordination site Schiff base ligand (H2L) as  well  as a β-diketonate auxiliary ligand.  The structures, magnetic properties, and catalytic performance of clusters 1–3have been studied. X-ray crystallography data revealed that clusters 1–3possess similar structures with two chair-form Ln4cores bridged by four μ3-O atoms. Clusters 1–3display extensive and high solvent stability. Magnetic analysis exhibits that cluster 1possesses a comparably large magnetocaloric effect (−ΔSm= 33.06 J kg–1K–1at 2.0 K and 7.0 T). AC susceptibility measurement suggests that cluster 2exhibits single-molecule magnet behavior under zero-field conditions. What’s more, all clusters can effectively convert CO2with epoxides. The highest yield is 98% at 70 °C 0.1 MPa catalyzed by 1. In addition, cluster 1can be reused three times with a negligible loss of catalytic activity.